/*
Copyright (C) 1996-1997 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include "common.h"

#define	ZONE_DEFAULT_SIZE	0x80000		//512kb

#define	ZONEID	0x1d4a11
#define MINFRAGMENT	64

typedef struct memblock_s {
	int		size;           // including the header and possibly tiny fragments
	int     tag;            // a tag of 0 is a free block
	int     id;        		// should be ZONEID
	struct memblock_s       *next, *prev;
	int		pad;			// pad to 64 bit boundary
} memblock_t;

typedef struct {
	int			size;		// total bytes malloced, including header
	memblock_t	blocklist;	// start / end cap for linked list
	memblock_t	*rover;
} memzone_t;

void Cache_FreeLow (int new_low_hunk);
void Cache_FreeHigh (int new_high_hunk);

//Use it instead of malloc so that if memory allocation fails,
//the program exits with a message saying there's not enough memory
//instead of crashing after trying to use a NULL pointer
void *Q_Malloc (size_t size) {
	void *p;

	if (!(p = malloc(size)))
		Sys_Error ("Not enough memory free; check disk space");

	return p;
}

//Use it instead of calloc so that if memory allocation fails,
//the program exits with a message saying there's not enough memory
//instead of crashing after trying to use a NULL pointer
void *Q_Calloc (size_t n, size_t size) {
	void *p;

	if (!(p = calloc(n, size)))
		Sys_Error ("Not enough memory free; check disk space");

	return p;
}

/*
==============================================================================
						ZONE MEMORY ALLOCATION

There is never any space between memblocks, and there will never be two
contiguous free memblocks.

The rover can be left pointing at a non-empty block

The zone calls are pretty much only used for small strings and structures,
all big things are allocated on the hunk.
==============================================================================
*/

memzone_t	*mainzone;

void Z_ClearZone (memzone_t *zone, int size) {
	memblock_t *block;

	// set the entire zone to one free block

	zone->blocklist.next = zone->blocklist.prev = block = (memblock_t *) ((byte *) zone + sizeof(memzone_t) );
	zone->blocklist.tag = 1;	// in use block
	zone->blocklist.id = 0;
	zone->blocklist.size = 0;
	zone->rover = block;

	block->prev = block->next = &zone->blocklist;
	block->tag = 0;			// free block
	block->id = ZONEID;
	block->size = size - sizeof(memzone_t);
}

void Z_Free (void *ptr) {
	memblock_t	*block, *other;

	if (!ptr)
		Sys_Error ("Z_Free: NULL pointer");

	block = (memblock_t *) ( (byte *)ptr - sizeof(memblock_t));
	if (block->id != ZONEID)
		Sys_Error ("Z_Free: freed a pointer without ZONEID");
	if (block->tag == 0)
		Sys_Error ("Z_Free: freed a freed pointer");

	block->tag = 0;		// mark as free

	other = block->prev;
	if (!other->tag) {	// merge with previous free block
		other->size += block->size;
		other->next = block->next;
		other->next->prev = other;
		if (block == mainzone->rover)
			mainzone->rover = other;
		block = other;
	}

	other = block->next;
	if (!other->tag) {	// merge the next free block onto the end
		block->size += other->size;
		block->next = other->next;
		block->next->prev = block;
		if (other == mainzone->rover)
			mainzone->rover = block;
	}
}

void *Z_Malloc (int size) {
	void *buf;

	//	Z_CheckHeap ();	// DEBUG
	buf = Z_TagMalloc (size, 1);
	if (!buf)
		Sys_Error ("Z_Malloc: failed on allocation of %i bytes",size);
	memset (buf, 0, size);

	return buf;
}

void *Z_TagMalloc (int size, int tag) {
	int extra;
	memblock_t	*start, *rover, *new, *base;

	if (!tag)
		Sys_Error ("Z_TagMalloc: tried to use a 0 tag");

	// scan through the block list looking for the first free block of sufficient size
	size += sizeof(memblock_t);	// account for size of block header
	size += 4;					// space for memory trash tester
	size = (size + 7) & ~7;		// align to 8-byte boundary

	base = rover = mainzone->rover;
	start = base->prev;

	do {
		if (rover == start)	// scaned all the way around the list
			return NULL;
		if (rover->tag)
			base = rover = rover->next;
		else
			rover = rover->next;
	} while (base->tag || base->size < size);

	// found a block big enough
	extra = base->size - size;
	if (extra >  MINFRAGMENT) {	// there will be a free fragment after the allocated block
		new = (memblock_t *) ((byte *)base + size );
		new->size = extra;
		new->tag = 0;			// free block
		new->prev = base;
		new->id = ZONEID;
		new->next = base->next;
		new->next->prev = new;
		base->next = new;
		base->size = size;
	}

	base->tag = tag;				// no longer a free block

	mainzone->rover = base->next;	// next allocation will start looking here

	base->id = ZONEID;

	// marker for memory trash testing
	*(int *)((byte *)base + base->size - 4) = ZONEID;

	return (void *) ((byte *)base + sizeof(memblock_t));
}

void Z_Print (memzone_t *zone) {
	memblock_t	*block;

	Com_Printf ("zone size: %i  location: %p\n",mainzone->size,mainzone);

	for (block = zone->blocklist.next; ; block = block->next) {
		Com_Printf ("block:%p    size:%7i    tag:%3i\n", block, block->size, block->tag);

		if (block->next == &zone->blocklist)
			break;			// all blocks have been hit	
		if ( (byte *) block + block->size != (byte *)block->next)
			Com_Printf ("ERROR: block size does not touch the next block\n");
		if (block->next->prev != block)
			Com_Printf ("ERROR: next block doesn't have proper back link\n");
		if (!block->tag && !block->next->tag)
			Com_Printf ("ERROR: two consecutive free blocks\n");
	}
}

void Z_CheckHeap (void) {
	memblock_t *block;
	
	for (block = mainzone->blocklist.next; ; block = block->next) {
		if (block->next == &mainzone->blocklist)
			break;			// all blocks have been hit	
		if ( (byte *)block + block->size != (byte *)block->next)
			Sys_Error ("Z_CheckHeap: block size does not touch the next block");
		if ( block->next->prev != block)
			Sys_Error ("Z_CheckHeap: next block doesn't have proper back link");
		if (!block->tag && !block->next->tag)
			Sys_Error ("Z_CheckHeap: two consecutive free blocks");
	}
}

//============================================================================

#define	HUNK_SENTINAL	0x1df001ed

typedef struct {
	int		sentinal;
	int		size;		// including sizeof(hunk_t), -1 = not allocated
	char	name[8];
} hunk_t;

byte	*hunk_base;
int		hunk_size;

int		hunk_low_used;
int		hunk_high_used;

qboolean	hunk_tempactive;
int			hunk_tempmark;

//Run consistancy and sentinal trahing checks

void Hunk_Check (void) {
	hunk_t	*h;
	
	for (h = (hunk_t *)hunk_base; (byte *)h != hunk_base + hunk_low_used; ) {
		if (h->sentinal != HUNK_SENTINAL)
			Sys_Error ("Hunk_Check: trashed sentinal");
		if (h->size < 16 || h->size + (byte *) h - hunk_base > hunk_size)
			Sys_Error ("Hunk_Check: bad size");
		h = (hunk_t *)((byte *) h + h->size);
	}
}

//If "all" is specified, every single allocation is printed.
//Otherwise, allocations with the same name will be totaled up before printing.
void Hunk_Print (qboolean all) {
	hunk_t *h, *next, *endlow, *starthigh, *endhigh;
	int count, sum, totalblocks;
	char name[9];

	name[8] = 0;
	count = 0;
	sum = 0;
	totalblocks = 0;

	h = (hunk_t *)hunk_base;
	endlow = (hunk_t *)(hunk_base + hunk_low_used);
	starthigh = (hunk_t *)(hunk_base + hunk_size - hunk_high_used);
	endhigh = (hunk_t *)(hunk_base + hunk_size);

	Com_Printf ("          :%8i total hunk size\n", hunk_size);
	Com_Printf ("-------------------------\n");

	while (1) {
		// skip to the high hunk if done with low hunk
		if ( h == endlow ) {
			Com_Printf ("-------------------------\n");
			Com_Printf ("          :%8i REMAINING\n", hunk_size - hunk_low_used - hunk_high_used);
			Com_Printf ("-------------------------\n");
			h = starthigh;
		}
		
		// if totally done, break
		if ( h == endhigh )
			break;

		// run consistancy checks
		if (h->sentinal != HUNK_SENTINAL)
			Sys_Error ("Hunk_Check: trashed sentinal");
		if (h->size < 16 || h->size + (byte *)h - hunk_base > hunk_size)
			Sys_Error ("Hunk_Check: bad size");
			
		next = (hunk_t *)((byte *)h+h->size);
		count++;
		totalblocks++;
		sum += h->size;

		// print the single block
		memcpy (name, h->name, 8);
		if (all)
			Com_Printf ("%8p :%8i %8s\n",h, h->size, name);

		// print the total
		if (next == endlow || next == endhigh || strncmp (h->name, next->name, 8)) {
			if (!all)
				Com_Printf ("          :%8i %8s (TOTAL)\n",sum, name);
			count = 0;
			sum = 0;
		}

		h = next;
	}

	Com_Printf ("-------------------------\n");
	Com_Printf ("%8i total blocks\n", totalblocks);
	
}

void *Hunk_AllocName (int size, char *name) {
	hunk_t	*h;

#ifdef PARANOID
	Hunk_Check ();
#endif

	if (size < 0)
		Sys_Error ("Hunk_Alloc: bad size: %i", size);

	size = sizeof(hunk_t) + ((size + 15) & ~15);

	if (hunk_size - hunk_low_used - hunk_high_used < size)
	  	Sys_Error ("Not enough RAM allocated.  Try using \"-mem 16\" on the FuhQuake command line.");

	h = (hunk_t *)(hunk_base + hunk_low_used);
	hunk_low_used += size;

	Cache_FreeLow (hunk_low_used);

	memset (h, 0, size);

	h->size = size;
	h->sentinal = HUNK_SENTINAL;
	strncpy (h->name, name, 8);

	return (void *) (h + 1);
}

void *Hunk_Alloc (int size) {
	return Hunk_AllocName (size, "unknown");
}

int	Hunk_LowMark (void) {
	return hunk_low_used;
}

void Hunk_FreeToLowMark (int mark) {
	if (mark < 0 || mark > hunk_low_used)
		Sys_Error ("Hunk_FreeToLowMark: bad mark %i", mark);
	memset (hunk_base + mark, 0, hunk_low_used - mark);
	hunk_low_used = mark;
}

int	Hunk_HighMark (void) {
	if (hunk_tempactive) {
		hunk_tempactive = false;
		Hunk_FreeToHighMark (hunk_tempmark);
	}
	return hunk_high_used;
}

void Hunk_FreeToHighMark (int mark) {
	if (hunk_tempactive) {
		hunk_tempactive = false;
		Hunk_FreeToHighMark (hunk_tempmark);
	}
	if (mark < 0 || mark > hunk_high_used)
		Sys_Error ("Hunk_FreeToHighMark: bad mark %i", mark);
	memset (hunk_base + hunk_size - hunk_high_used, 0, hunk_high_used - mark);
	hunk_high_used = mark;
}

void *Hunk_HighAllocName (int size, char *name) {
	hunk_t *h;

	if (size < 0)
		Sys_Error ("Hunk_HighAllocName: bad size: %i", size);

	if (hunk_tempactive) {
		Hunk_FreeToHighMark (hunk_tempmark);
		hunk_tempactive = false;
	}

#ifdef PARANOID
	Hunk_Check ();
#endif

	size = sizeof(hunk_t) + ((size+15)&~15);

	if (hunk_size - hunk_low_used - hunk_high_used < size)
	  	Sys_Error ("Not enough RAM allocated.  Try using \"-mem 16\" on the FuhQuake command line.");

	hunk_high_used += size;
	Cache_FreeHigh (hunk_high_used);

	h = (hunk_t *) (hunk_base + hunk_size - hunk_high_used);

	memset (h, 0, size);
	h->size = size;
	h->sentinal = HUNK_SENTINAL;
	strncpy (h->name, name, 8);

	return (void *) (h + 1);
}

//Return space from the top of the hunk
void *Hunk_TempAlloc (int size) {
	void *buf;

	size = (size + 15) & ~15;

	if (hunk_tempactive) {
		Hunk_FreeToHighMark (hunk_tempmark);
		hunk_tempactive = false;
	}

	hunk_tempmark = Hunk_HighMark ();

	buf = Hunk_HighAllocName (size, "temp");

	hunk_tempactive = true;

	return buf;
}

/*
===============================================================================
CACHE MEMORY
===============================================================================
*/

typedef struct cache_system_s {
	int						size;		// including this header
	cache_user_t			*user;
	char					name[16];
	struct cache_system_s	*prev, *next;
	struct cache_system_s	*lru_prev, *lru_next;	// for LRU flushing	
} cache_system_t;

cache_system_t *Cache_TryAlloc (int size, qboolean nobottom);

cache_system_t	cache_head;

void Cache_Move ( cache_system_t *c) {
	cache_system_t		*new;

	// we are clearing up space at the bottom, so only allocate it late
	new = Cache_TryAlloc (c->size, true);
	if (new) {
		//cache move worked
		memcpy ( new + 1, c + 1, c->size - sizeof(cache_system_t) );
		new->user = c->user;
		memcpy (new->name, c->name, sizeof(new->name));
		Cache_Free (c->user);
		new->user->data = (void *) (new + 1);
	} else {
		//cache move failed
		Cache_Free (c->user);		// tough luck...
	}
}

//Throw things out until the hunk can be expanded to the given point
void Cache_FreeLow (int new_low_hunk) {
	cache_system_t *c;
	
	while (1) {
		c = cache_head.next;
		if (c == &cache_head)
			return;		// nothing in cache at all
		if ((byte *) c >= hunk_base + new_low_hunk)
			return;		// there is space to grow the hunk
		Cache_Move (c);	// reclaim the space
	}
}

//Throw things out until the hunk can be expanded to the given point
void Cache_FreeHigh (int new_high_hunk) {
	cache_system_t *c, *prev;

	prev = NULL;
	while (1) {
		c = cache_head.prev;
		if (c == &cache_head)
			return;		// nothing in cache at all
		if ((byte *) c + c->size <= hunk_base + hunk_size - new_high_hunk)
			return;		// there is space to grow the hunk
		if (c == prev) {
			Cache_Free (c->user);	// didn't move out of the way
		} else {
			Cache_Move (c);	// try to move it
			prev = c;
		}
	}
}

void Cache_UnlinkLRU (cache_system_t *cs) {
	if (!cs->lru_next || !cs->lru_prev)
		Sys_Error ("Cache_UnlinkLRU: NULL link");

	cs->lru_next->lru_prev = cs->lru_prev;
	cs->lru_prev->lru_next = cs->lru_next;

	cs->lru_prev = cs->lru_next = NULL;
}

void Cache_MakeLRU (cache_system_t *cs) {
	if (cs->lru_next || cs->lru_prev)
		Sys_Error ("Cache_MakeLRU: active link");

	cache_head.lru_next->lru_prev = cs;
	cs->lru_next = cache_head.lru_next;
	cs->lru_prev = &cache_head;
	cache_head.lru_next = cs;
}

//Looks for a free block of memory between the high and low hunk marks
//Size should already include the header and padding
cache_system_t *Cache_TryAlloc (int size, qboolean nobottom) {
	cache_system_t *cs, *new;

	// is the cache completely empty?
	if (!nobottom && cache_head.prev == &cache_head) {
		if (hunk_size - hunk_high_used - hunk_low_used < size)
			Sys_Error ("Cache_TryAlloc: %i is greater then free hunk", size);

		new = (cache_system_t *) (hunk_base + hunk_low_used);
		memset (new, 0, sizeof(*new));
		new->size = size;

		cache_head.prev = cache_head.next = new;
		new->prev = new->next = &cache_head;

		Cache_MakeLRU (new);
		return new;
	}

	// search from the bottom up for space
	new = (cache_system_t *) (hunk_base + hunk_low_used);
	cs = cache_head.next;

	do {
		if (!nobottom || cs != cache_head.next) {
			if ( (byte *)cs - (byte *)new >= size) {	
				// found space
				memset (new, 0, sizeof(*new));
				new->size = size;

				new->next = cs;
				new->prev = cs->prev;
				cs->prev->next = new;
				cs->prev = new;

				Cache_MakeLRU (new);

				return new;
			}
		}

		// continue looking		
		new = (cache_system_t *)((byte *)cs + cs->size);
		cs = cs->next;

	} while (cs != &cache_head);

	// try to allocate one at the very end
	if (hunk_base + hunk_size - hunk_high_used - (byte *) new >= size) {
		memset (new, 0, sizeof(*new));
		new->size = size;

		new->next = &cache_head;
		new->prev = cache_head.prev;
		cache_head.prev->next = new;
		cache_head.prev = new;

		Cache_MakeLRU (new);

		return new;
	}

	return NULL;		// couldn't allocate
}

//Throw everything out, so new data will be demand cached
void Cache_Flush (void) {
	while (cache_head.next != &cache_head)
		Cache_Free (cache_head.next->user);	// reclaim the space
}

void Cache_Print (void) {
	cache_system_t *cd;

	for (cd = cache_head.next; cd != &cache_head; cd = cd->next) {
		Com_Printf ("%8i : %s\n", cd->size, cd->name);
	}
}

void Cache_Report (void) {
	Com_DPrintf ("%4.1f megabyte data cache\n", (hunk_size - hunk_high_used - hunk_low_used) / (float)(1024*1024) );
}

void Cache_Init (void) {
	cache_head.next = cache_head.prev = &cache_head;
	cache_head.lru_next = cache_head.lru_prev = &cache_head;

	Cmd_AddCommand ("flush", Cache_Flush);
}

//Frees the memory and removes it from the LRU list
void Cache_Free (cache_user_t *c) {
	cache_system_t	*cs;

	if (!c->data)
		Sys_Error ("Cache_Free: not allocated");

	cs = ((cache_system_t *)c->data) - 1;

	cs->prev->next = cs->next;
	cs->next->prev = cs->prev;
	cs->next = cs->prev = NULL;

	c->data = NULL;

	Cache_UnlinkLRU (cs);
}

void *Cache_Check (cache_user_t *c) {
	cache_system_t	*cs;

	if (!c->data)
		return NULL;

	cs = ((cache_system_t *)c->data) - 1;

	// move to head of LRU
	Cache_UnlinkLRU (cs);
	Cache_MakeLRU (cs);

	return c->data;
}

void *Cache_Alloc (cache_user_t *c, int size, char *name) {
	cache_system_t	*cs;

	if (c->data)
		Sys_Error ("Cache_Alloc: already allocated");

	if (size <= 0)
		Sys_Error ("Cache_Alloc: size %i", size);

	size = (size + sizeof(cache_system_t) + 15) & ~15;

	// find memory for it	
	while (1) {
		if ((cs = Cache_TryAlloc (size, false)))	{
			strncpy (cs->name, name, sizeof(cs->name)-1);
			c->data = (void *)(cs+1);
			cs->user = c;
			break;
		}

		// free the least recently used cahedat
		if (cache_head.lru_prev == &cache_head)
			Sys_Error ("Cache_Alloc: out of memory");
													// not enough memory at all
		Cache_Free ( cache_head.lru_prev->user );
	}

	return Cache_Check (c);
}

//============================================================================

void Memory_Init (void *buf, int size) {
	int p, zonesize = ZONE_DEFAULT_SIZE;

	hunk_base = buf;
	hunk_size = size;
	hunk_low_used = 0;
	hunk_high_used = 0;

	Cache_Init();
	if ((p = COM_CheckParm ("-zone")) && p + 1 < com_argc)
		zonesize = Q_atoi (com_argv[p + 1]) * 1024;

	mainzone = Hunk_AllocName (zonesize, "zone");
	Z_ClearZone (mainzone, zonesize);
}